In the 9th we didn't have actual rucksacks as far as I know, we were weren't out very long most of the time being the reason why. Too wet. But we carried as little as possible when we did stay out over any time. If we had an alice pack, our version of a ruck, we carried C's , although otherwise in a sock tied to our gear when we didn't. We carried a poncho and a poncho liner if we were going to be out a night or two, although one or the other of these was as likely to be tied to the pack as often as in it. Some carried an extra pair of socks, although I didn't wear socks. Some might have carried a tooth brush, but not many. Possibly some small articles like shaving equipment or writting materials, although, again, not many, since we weren't out all that long. We had bug juice. We had maybe a strip of cloth for a headband. We would carry extra cigarettes. There might have been extra ammo, but not likely as we liked all of our ammo to be where we could get to it quickly if possible. During times when steel pots were required there may have been a jungle hat in the alice pack also.

There might have been things tied to the pack. Hand flairs and smoke granades being two possiblilities. Could be trip flairs in or attached also.

When I humped a radio I had a small green bag attached to the bottom of the ruck frame the radio was tied to. In this bag I carried my C's and assorted other items like the bug juice.

Good question. Maybe somebody will answer besides me.

Here is a picture to give a better idea. That's me on the left and my alice pack on the ground to the left. To the right is my RTO Joe Delgato and his radio attacted to a pack frame.

This is a better picture of what an RTO would carry. Canvas bag at the bottom for "stuff" like C's and bug juice. Above that an extra radio battery in a cardboard box ( the battery was sealed in heavy duty plastic to guard against water). Above that were hand flairs. Then the PRC25 radio. A poncho and or poncho liner tied to the back of the radio. Note canteens held by d rings to the frame. There were often as not smoke granades tied to the rig somewhere also.